Hla-b27
 

My daughter is experiencing arthritic issue in her knee. They tested her for a gene called HLA-B27. I researched it and it is related to a host of issues including MG. Has anyone else been tested for this gene or had it used in suspecting MG?
I hope to follow up w/ my neuro at the first of the year to do some more testing. I will remain curious until then if I should be tested for this Gene or not.
My only diagnosis is from a positive modulating ACHr test and a droopy eye. Not to mention extreme fatigue and laryngeal issues that are exacerbated by stress, mental or physical.

HLA-B27 is a member of what are called the Class I MHC proteins, which are found on most cells in the body.

The main job of Class I MHC proteins is to help defending against virus infections. When a cell is infected with a virus fragments of proteins made by the virus will end off bound to Class I MHC proteins on its surface. These are recognised by immune system cells (cytotoxic T cells) which kill the cell, stopping the virus from replicating.

However, sometimes this goes wrong. Inheriting HLA-B27 is a risk factor for ankylosing spondylitis, which is an inflammatory auto-immune disease. Essentially what happens in this case is that cytotoxic T cells "make a mistake" and kill normal body cells, "thinking" that they are infected with a virus.

As far as I can see (a PubMed search) inheriting HLA-B27 is not a known risk factor for myasthenia gravis.

I hope this is not too technical and trust that it makes sense.

Thank you for your brief look into the relation of HLA-B27 to MG. Yes it is more relating to AS (ankylosing spondylitis) which I also have thus my piqued interest. There is a stronger relation of MG to HLA-B8, however in late onset of MG in Males (age 60-80) there is an association with HLA-B27.

http://eyewiki.aao.org/Myasthenia_Gravis

"The disease has a bimodal pattern, having an early peak in the second and third decade, and a late peak in the sixth to eighth decade. The early peak shows a female predominance, approximately 3:1, and an association with HLA-B8, HLA-DR3, and HLA-DR1, the latter being more specific for ocular MG. Interestingly, the late peak features a male predominance and an association with HLA-B27 and HLA-DR2"

This is another good link to the dysfunction of the T cell and the genetic link to MG:
http://europepmc.org/backend/ptpmcre...8&blobtype=pdf

Thanks for that Bakerman.

You might find this recent genome-wide association study interesting; http://www.ncbi.nlm.nih.gov/pubmed/25643325 .

The major genetic risk factors for MG were mutations in CTLA4 (CD152) and HLA-DQA1.

CD152 is found on helper T cells and drugs which modulate it have been approved from treatment of other auto-immune diseases. As the authors point out, clinical trials of these drugs in the context of MG look like a good idea.

HLA-DQA1 is a Class II MHC protein. Given the (indirect) role of Class II MHC proteins in antibody production, these mutation might explain why self-reactive antibodies are common in people with MG though I doubt that this will help much in terms of clinical intervention.